Spinning of



Jan. 31, 1956 w. H. BRADSHAW ET AL 2,

SPINNING OF FILAMENTARY MATERIALS 2 Sheets-Sheet '1 Filed April 30, 1952 [llli INVENTORS.

S mm n N RE 30 0 o n M A IL ME 5 m WR Jan. 31, 1956 w. H. BRADSHAW ET AL 2,732,536

SPINNING OF FILAMENTARY MATERIALS 2 Sheets-Sheet 2 Filed April 30, 1952 FIG.2.

INVENTORS. W|LL|AM H. BRADSHAW RUSSELL O. DENYES Y r ATTORNEYS.

United States Patent 2,732,586 SPINNING OF FILAMENTARY MATERIALS William H. Bradshaw, New Rochelle, N. Y., and Russell 0. Denyes, Maplewood, N. J., assignors to Celanese Corporation of America, New York, N. Y., a corpora tion of Delaware Application April 30, 1952, Serial No. 285,238 14 Claims. (Cl. 18-8) This invention relates to the spinning of filamentary materials and is particularly concerned with the wet spinning of filamentary materials having a basis of an organic acid ester of cellulose.

An important object of this invention is to provide a process and apparatus for the wet-spinning of filamentary materials having a basis of an organic acid ester of cellulose which will consistently yield products having uniform, desirable properties.

Other objects of this invention, together with certain details of construction and combinations of parts, will be apparent from the following detailed description and claims.

In the production of high tenacity organic derivative of cellulose filamentary materials by the wet-spinning process, a spinning dope comprising a solution of an organic derivative of cellulose material is pumped or otherwise forced through a spinnerette, containing one or more apertures therein, into a liquid coagulating medium containing a solvent or plasticizing. agent, hereinafter referred to as a plasticizing agent, for the organic derivative of cellulose. As the filaments flow through the coagulating medium, a suflicient tension is applied thereto to cause the filamentary materials to stretch, the degree of stretch determining to a large extent the properties of the final products. The organic derivative of cellulose filamentary materials prepared in this manner may be used as such or they may be saponified, in a manner Well known in the art, further to increase their tenacity.

It has now been found that close control must be maintained over the conditions during each part of the spinning operation to obtain products having uniform, desirable properties. As emerge from the spinnerette, which is preferably of the type shown in the copending application of R. O. Denyes, Serial No. 224,352, filed May 3, 1951, now Patent No. 2,673,368, into a spin pot through which the coagulating medium flows, care must be taken substantially to prevent disturbance of the filamentary materials and the coagulating medium immediately surrounding them if undesirable variations in the properties of the filamentary material are to be avoided. An arrangement that has been found suitable for substantially preventing the development of turbulence in the coagulating medium, comprises an annular distributing head which will discharge the coagulating medium into the spin pot at a plurality of points spaced aboutits periphery, together with a screen which encloses the spinnerette and through which the coagulating medium must flow to come into contact with the filamentary materials. The filamentary materials and the coagulating medium are then caused to flow upwardly through a spin tube into a second spin pot into which a further quantity of coagulating medium is introduced, again taking care to obtain a uniform distribution of the coagulating medium as it enters the second spin pot and the filamentary materials approaches the filamentary materials. From the second spin pot, the filamentary materials and all the coagulating medium flow upwardly into a second spin tube where in the coagulation of the filamentary materials is completed to the desired extent. To impart the desired degree of stretch to the filamentary materials, which may range from about 500 to 12,800%, or more, means, of any conventional type, are provided to control the rate of delivery of the spinning dope through the spinnerette and to control the rate of withdrawal of the filamentary materials from the second spin tube.

As will be described more fully hereinafter, it has been found essential, in order to obtain filamentary mato employ spin tubes having an internal diameter bearing a definite terials having uniform, desirable properties,

relationship to the diameter of the bundle of filaments being produced and to maintain a definite relationship between the velocity of the filamentary materials and the stream of coagulating medium flowing through the spin tubes.

Among the organic derivative of cellulose materials that may be employed for the production of filamentary materials in this manner, there may be mentioned cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate and the like. terials may be dissolved in any suitable solvents, including, for example, acetone-water mixtures, diacetone, nitromethylene, acetic acid, methyl acetate, various chlorinated hydrocarbons especially in conjunction with alcohol such as methylene chloride, ethyl chloride, etc. and methyl ethyl ketone to form the spinning dope. The coagulating medium may be aqueous or non-aqueous in nature and may contain, as the plasticizing agent for the organic derivative of cellulose material, any suitable substance, such as, for example, acetone, diacetone alcohol, acetic acid, formic acid, ethyl lactate, zinc chloride, thiocyanates, such as sodium, potassium or ammonium thiocyanate and various chlorinated hydrocarbons such as methylene chloride, ethyl chloride and mixtures of chlorinated hydrocarbons.

A preferred embodiment of this invention is shown in the accompanying drawings wherein Fig. 1 is a front elevational view of apparatus, and

Fig. 2 is a cross-sectional view, of the lower spin pot.

Referring now to the drawings, the reference numeral 11 designates generally alower spin pot comprising a cylindrical chamber 12 to the top of which a cover 13 is secured by means of wing nuts 14 and bolts 15 mounted in pad eyes 16 fastened to the walls of the said chamber 12.. A spinning dope is pumped into the lower spin pot 11 through a conduit 17 which discharges into a spinning head, indicated generally by reference the spinning on an enlarged scale,

numeral 18. The spinning head 18 comprises a filter unit 19 and aspinnerette tures 21 therein through The filter unit 19 and the between a lower fitting A coagulating or setting medium, which will cause the filaments 22. to coagulate or set, is introduced into the lower spin pot 11 through a conduit 25 which discharges the said coagulating medium into an annular distributing head 26 extending around the periphery of the chamber 12. The annular distributing head 26 is formed by ah upper plate 27 which extends from the wall of the chamber 12 to the lower fitting 23, a lower plate 28 which ex- Patented Jan. 31, 19 56 These organic derivatives of cellulose ma-' tends from a point slightly spaced from the wall of the chamber 12 to a fitting 29 fastened to the conduit 17, and a cylindrical tube 31 that is positioned concentrically of the wall of the chamber 12 and extends from the upper plate 27 to the lower plate 28. After filling the annular passageway 26, the coagulating medium flows through a plurality of apertures 32 in the cylindrical tube 31 and then upwardly through a plurality of apertures 33 in the upper plate 27 to fill the main body of the chamber 12. From the chamber 12, the coagulating medium flows through a cylindrically shaped screen 34, which surrounds thespinnerette 20, and then fiows upwardly, with the filaments 22, through a tube 35 which is suspended from the cover 13 by means of an adapter ring 36. By bringing the coagulating medium into contact with the filaments 22 in the manner described, the development of turbulence in the said medium is substantially prevented, thereby insuringthat the coagulation of all the filaments 22 will take place under substantially uniform conditions.

The filaments 22 and the coagulating medium then flow upwardly through a lower spin tube 37 which extends through a gasket 38, maintained in position by means of a ring 39, into abutment with the tube 35. The lower spin tube 37 consists of three sections, a bottom cylindrical section 41, an intermediate inwardly tapered section 42, and an upper cylindrical section 43. The dimensions of the lower spin tube 37, as well as of the screen 34 and the tube 35, must be maintained within close limits relative to the diameter of the bundle of filaments 22 to obtain filaments having uniform, desirable properties. general, the internal diameter of the lower spin tube 37, the screen 34 and the tube 35 should exceed the diameter of the bundle of filaments 22 by at most about 1 inch at any point along the length of any of its three sections. It has been found that when there is a greater difference between the internal diameter of the lower spin tube 37 and the diameter of the bundle of filaments 22, there is a tendency for circulatory currents to develop between the bundle of filaments and the wall of the spin tube, which will affect the properties of at least some of the filaments 22 in an undesirable manner. In addition, it has been found that the best results are obtained when the spin tube 37 is tapered inwardly along its length so as to reduce its internal diameter at a distance of between about and inches from the face of the spinnerette 20 to between about and 85% of its internal diameter adjacent to the spinnerette.

The filaments 22 and the coagulating medium emerge from the lower spin tube 37 into an upper spin pot, indicated generally by reference numeral 4-1, comprising a cylindrical chamber 45 into which the lower spin tube 37 projects for a short distance. An additional quantity of coagulating medium is introduced into the upper spin pot 44 through a conduit 46 into the upper portion of an annular distributing head 47 provided with a plurality of perforations 48 leading to the lower portion thereof from which the coagulating medium flows into the upper spin pot 44 through perforations 48' distributed about the outer periphery of the said annular distributing head 47. The head 47 serves to reduce to a minimum the disturbance of the filamentary materials by supplying the additional coagulating medium uniformly around the entire bundle of filamentary materials. The filaments 22 and all the coagulating medium flow from the upper spin pot 44 into an upper spin tube 49 which is aligned with the lower spin tube 37 and which projects through the top of and into the upper spin pct 44. Advantageously, the upper spin tube 49 is positioned so that its lower end is spaced between about /2 and 2 /2 inches from the upper end of the lower spin tube 37. The internal diameter of the upper spin tube 49 should be equal, in general, to the internal diameter of the upper end of the lower spin tube 37.

Upon emergence from the upper spin tube 49, the filaments 22 may be separated from the coagulating medium in any suitable manner, as for example, by means of the apparatus disclosed in the application of Edward T. Jones, Jr., Serial No. 261,439, filed December 13, 1951, now Patent No. 2,674,112. The filaments 22 may then be washed, dried and wound into a package, or they may be continuously saponified, washed and dried before being wound into a package, all in a manner well known in the art.

The distribution of apertures 21 in the face of the spinnerette 20 can take a number of different patterns. However, for spinnerettes having more than about 300 apertures therein, the best results are obtained when the apertures are arranged in the manner disclosed in the Denyes application referred to above. When using this arrangement, spinnerettes having up to 300 apertures preferably have a 1.5 inch diameter face; spinnerettes having over 300 and up to 550 apertures preferably have 2 inch diameter face; spinnerettes having over 550 and up to 1400 apertures preferably have a 3 inch diameter face; and spinnerettes having over 1400 apertures have a 4 inch, or larger, diameter face. The diameter of the spinnerette face may be expressed by the equation 7 N d-0.2- :l:0.a where d equals the diameter of the spinnerette face in inches and N equals the number of apertures. The internal diameter of the lower end of the lower spin tube 37 is defined by the same equation.

To obtain filamentary materials having the most desirable properties, the internal diameter of the upper end of the lower spin tube 37 should bear a definite relationship to the internal diameter of the lower end of said lower spin tube. This relationship may be expressed by the formula Where 0." equals the internal diameter of the upper end of the lower spin tube and d has the meaning given above. The internal diameter of the lower end of the upper spin tube 49 is defined by the same equation.

The amount of coagulating medium introduced into the lower spin pot 11 should be controlled to give a definite concentration of solvent and plasticizing agent around each of the filaments 22, particularly for a distance of about 5 inches upwardly from the point where the file.- ments 22 emerge from the spinnerette 20 to obtain products having the most desirable properties. It has been found that if an insuificient amount of coagulating medium is introduced into the lower spin pct 11, the filaments 22 tend to break, interrupting the continuity of spinning. It has also been found that if the amount of coagulating medium introduced into the lower spin pct 11 is increased to at least about the minimum necessary to avoid breakage of the filaments 22 or preferably to about said minimum, products are obtained having the optimum physical properties. The amount of coagulating medium may be expressed by the equation where C equals the amount of coagulating medium in cubic centimeters per minute and N has the meaning given above. When the number of filaments being spun is less than l86(a'-O.25) the amount of coagulating medium used should be the same as when the number of filaments is equal to 186(d0.25)

The additional coagulating medium introduced into the upper spin pot 44 enables a close control to be ob tained of the temperature and concentration of solvent and plasticizing agent during the later stages of the setting of the filaments 22. Also by increasing the velocity of the coagulating medium in the upper spin. tube 49 with respect to the velocity of the filaments 22, the tension on the said filaments 22 as they leave the coagulating medium is reduced. The increased velocity of the coagulating medium the upper spin tube 29 also serves to maintain the filaments 22 in a straight line as they, pass through. the .upper i spinpot 44 from:; the lower spin tube 27 to the upper spin tube 49. H

The following examples are given to illustrate this invention further.

Examples as set forth in the following table:

Filament speed at take-up, meters/min 75 76 Number of apertures in spinnerette... 300 1, 400 Denier per filament 85 85 Diameter of spinnerette face inches 1. 5 3 Internal diameter of lower end of lower spin tube .in es. 1.5 3 Internal diameter of upper end of lower spin 0 531" iii If i "i fi 1 2 0a ating me um a e o ower spin p0 ee/ n 900 4. 00

oagu ating me ium a e 0 upper sp' pc I ccJmin .1. 1, 500 1, 500

In both cases the spinningcontinues without interruption and there is obtained a product having good physical properties.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filamentforming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the internal diameter of said spin tube exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along its length.

2. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filamentforming apertures invthe spinnerette into the coagulating medium to form a bundle of filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly fromthe spin pot, the internal diameter of the said spin tube exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along its length and the said spin tube tapering inwardly along its length so that its internal diameter at a distance of between about .10 and 25 inches from the face of the spinnerette is between about 50 and 85% of its internal diameter adjacent to the spinnerette.

3. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filamentforming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, a screen surrounding the spinnerette through which the coagulating medium flows into contact with the bundle of'filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the internal diameter of the said spin tube andthe said screen exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along its length.

4. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filament-forming apertures therein, an annular distributing head having a plurality of perforations about the periphery thereof positioned in said spin pot for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, a screen surrounding the spinnerette through which the coagulating medium flows into contact with the bundle of filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the internal diameter of the said spin tube and the said screen exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along its length.

5. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filament-forming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot,

, means for introducing a spinning dope into the spinning head .whereby'it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, a spin tube through which the coagulating mediumand the bundle of filaments pass upwardly from the spin pot, a second spin pot into which thecoagulathig medium and the bundle of filaments pass from the spin tube, means for introducing a further quantity of coherent liquid coagulating medium into said second spin pot, and a second spin tube extending from the second spin pot through which all coagulating medium and the bundle of filaments pass upwardly from the second spin pot, the inlet end or the said second spin tube being spaced between about /2 and 2V2 inches from the outlet end of the first spin tube.

6. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filament-forming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette. into the coagulating medium to form a bundle of filaments, a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, a second spin pot into which the coagulating medium and the bundle of filaments pass from the spin tube, means for introducing a further quantity of coherent liquid coagulating medium into said second spin pot, and a second spin tube extending from the second spin pot through which all the coagulating medium and the bundle of filaments pass upwardly from the second spin pot, the internal diameter of the said spin tubes exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along their length.

7. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filament-form ing apertures therein, an annular distributing head having a plurality of perforations about the periphery thereof positioned in said spin pot for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, a screen surrounding the spinnerette through which the coagulating medium flows into contact with the bundle of filaments, a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the internal diameter of the said screen and of the said spin tube exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along their length, the said spin tube tapering inwardly along its length so that its internal diameter at a distance of between about 10 and 25 inches from the face of the spinnerette is between about 50 and 85% of its internal diameter adjacent to the spinnerette, a second spin pot into which the coagulat ing medium and the bundle of filaments pass from the spin tube, means for introducing a further quantity of coherent liquid coagulating medium into said second spin pot, and a second cylindrical spin tube extending from the second spin pot through which all the coagulating medium and the bundle of filaments pass upwardly from the second spin pot, the inlet end of said second spin tube being spaced between about /2 and 2 /2 inches from the outlet end of the first spin tube and the internal diameter of the said second spin tube exceeding the diameter of the bundle of filaments by at most about 1 inch at any point along its length.

8. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the diameter of the spinnerette face being expressed by the equation where d is the diameter of the spinnerette face in inches and N is the number of filament-forming apertures in the spinnerette.

9. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filamentforming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the internal diameter of the lower end of the spin tube being expressed by the equation where d is the internal diameter of the lower end of the spin tube in inches and N is the number of filamentforming apertures in the spinnerette.

10. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, and a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, the internal diameter of the lower end of the spin tube being expressed by the equation where d is the internal diameter of the lower end of the spin tube in inches and N is the number of filament-forming apertures in the spinnerette, and where the internal diameter of the upper end of the spin tube is expressed by the equation where d is the internal diameter of the upper end of the spin tube in inches.

11. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said pin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, a second spin pot into which the coagulating medium and the bundle of filaments pass from the spin tube, means for introducing a further quantity of coherent liquid coagulating medium into said second spin pot, and a second cylindrical spin tube extending from the second spin pot through which all the coagulating medium and the bundle of filaments pass upwardly from the second spin pot, the internal diameter of the lower end of the lower spin tube being expressed by the equation where d is the internal diameter of the lower end of the lower spin tube in inches and N is the number of filamentforming apertures in the spinnerette.

12. In an apparatus for the spinning of filamentary materials, the combination with a spin pot, of a spinning head including a spinnerette having at least 300 filamentforming apertures therein, means for introducing a coherent mass of liquid coagulating medium into said spin pot, means for introducing a spinning dope into the spinning head whereby it will flow through the filament-forming apertures in the spinnerette into the coagulating medium to form a bundle of filaments, a spin tube through which the coagulating medium and the bundle of filaments pass upwardly from the spin pot, a second spin pot into which the coagulating medium and the bundle of filaments pass from the spin tube, means for introducing a further quantity of coherent liquid coagulating medium into said second spin pot, and a second cylindrical spin tube extending from the second spin pot through which all the coagulating medium and the bundle of filaments pass upwardly from the second spin pot, the internal diameter of the lower end of the lower spin tube being expressed by the equation where d is the internal diameter of the lower end of the lower spin tube in inches and N is the number of filament-forming apertures in the spinnerette, and where the internal diameter of the upper end of the lower spin tube is expressed by the equation where d is the internal diameter of the upper end of the spin tube in inches.

13. In a process for the production of filamentary materials by the spinning of a dope comprising a solution of an organic derivative of cellulose into a coherent mass of liquid coagulating medium containing a plasticiziug agent for the organic derivative of cellulose, the steps which comprise passing said dope through a spinnerette having at least 300 apertures therein into an enclosed coagulating zone to form a bundle of filaments, introducing a liquid coagulating medium into the coagulating zone around said spinnerette so as to envelop each of the newly formed filaments in said bundle with a coherent liquid mass, and passing said newly formed bundle and the coagulating medium from said coagulating zone upwardly through an elongated passageway having an internal diameter exceeding the diameter of said bundle of filaments by at most about 1 inch at any point along its length.

14. In a process for the production of filamentary materials by the spinning of a dope comprising a solution of an organic derivative of cellulose into a coherent mass of liquid coagulating medium containing a plasticizing agent for the organic derivative of cellulose, the steps which comprise passing said dope through a spinnerette having at least 300 apertures therein into an enclosed coagulating zone to form a bundle of filaments, introducing a liquid coagulating medium into the coagulating zone around said spinnerette so as to envelop each of the newly formed filaments in said bundle with a coherent liquid mass, and passing said newly formed bundle and the coagulating medium from said coagulating zone upwardly through an elongated passageway of varying crosssection, the internal diameter of said passageway exceeding the diameter of said bundle by at most about 1 inch at any point along its length, the internal diameter of the end of said passageway adjacent to said spinnerette being expressed by the equation where d is said internal diameter in inches and N is the number of filaments in said bundle, the internal diameter of the other end of said passageway being expressed by the equation d'=(0.67:t0.17)d where a" is said internal diameter in inches, the amount UNITED STATES PATENTS 827,434 Friedrich July 21, 1906 1,517,627 Hubert Dec. 2, 1924 1,997,930 Hoimann Apr. 16, 1935 2,027,419 Dreyfus Jan. 14, 1936 2,046,575 Ostermann et al July 7, 1936 2,046,576 Kumichel July 7, 1936 2,425,782 Bludworth et al. Apr. 19, 1947 

1. IN AN APPARATUS FOR THE SPINNING OF FILAMENTARY MATERIALS, THE COMBINATION WITH A SPIN POT, OF A SPINNING HEAD INCLUDING A SPINNERETTE HAVING AT LEAST 300 FILAMENTFORMING APERTURES THEREIN, MEANS FOR INTRODUCING A COHERENT MASS OF LIQUID COAGULATING MEDIUM INTO SAID SPIN POT, MEANS FOR INTRODUCING A SPINNING DOPE INTO THE SPINNING HEAD WHEREBY IT WILL FLOW THROUGH THE FILAMENTFORMING APERTURES IN THE SPINNERETTE INTO THE COAGULATING MEDIUM TO FORM A BUNDLE OF FILAMENTS, AND A SPIN TUBE THROUGH WHICH THE COAGULATING MEDIUM AND THE BUNDLE OF FILAMENTS PASS UPWARDLY FROM THE SPIN POT, THE INTERNAL DIAMETER OF SAID SPIN TUBE EXCEEDING THE DIAMETER OF THE BUNDLE OF FILAMENTS BY AT MOST ABOUT 1 INCH AT ANY POINT ALONG ITS LENGTH. 